KR20010053589A - Titanium-based composite material, method for producing the same and engine valve - Google Patents

Abstract

The titanium-based composite material of the present invention is a titanium-based composite material having a matrix containing titanium (Ti) alloy as a main component and titanium compound particles and / or rare earth compound particles dispersed in the matrix, wherein the matrix is 3.0 to 7.0 wt% Contains aluminum (Al), 2.0 to 6.0 wt% tin (Sn), 2.0 to 6.0 wt% zirconium (Zr), 0.1 to 0.4 wt% silicon (Si) and 0.1 to 0.5 wt% oxygen (O) The titanium compound particles occupy 1 to 10% by volume, and the rare earth compound particles occupy 3% by volume or less.

According to this composition, a titanium material excellent in heat resistance, hot workability, specific strength, and the like is obtained.

Description

Titanium-based composite material, method for producing the same and engine valve

Titanium alloys are used in various mechanical parts because of their high specific strength and excellent toughness. For example, titanium alloys are mainly used in the military, aerospace and aircraft fields, mainly in the United States and United Kingdom. In addition, in these fields, development of heat-resistant titanium alloys excellent in heat resistance is also in progress. However, since these heat-resistant titanium alloys are developed with an emphasis on performance, mass production is insufficient at high cost. In addition, heat-resistant titanium alloys are difficult to dissolve and form and have low yields. Therefore, such titanium materials are used only in limited fields.

However, in recent years, as the demand for high performance and light weight of machines increases, titanium materials, particularly titanium materials having excellent heat resistance, have been evaluated again in general mechanical fields such as automobiles. As an example of the titanium material which is excellent in such heat resistance, the engine / valve for automobiles is demonstrated below.

BACKGROUND ART Engines and valves for automobiles are conventionally installed at the inlet and exhaust ports of an engine and are important components that determine the characteristics of the engine's performance, for example, fuel economy, efficiency and output. In addition, the engine valve is at a high temperature exceeding 600 ° C. In particular, the valve of the exhaust system (exhaust valve) is at a much higher temperature than the valve of the intake system (intake valve). For example, even in a mass production engine, since an exhaust valve is exposed to high temperature exhaust, it may become around 800 degreeC. Therefore, the exhaust valve is required to have excellent heat resistance. The conventional exhaust valve for mass production uses heat-resistant steel, such as JIS standard SUH35.

However, when heat-resistant steel such as SUH 35 is used for reciprocating parts such as valves, the specific gravity is high, so the inertia weight thereof becomes large. Therefore, the maximum rotation speed is limited, and it is necessary to increase the spring load, which increases the friction and hinders the high performance of the engine.

For this reason, it is considered to use titanium materials excellent in specific strength and the like for engines and valves. Titanium material is very attractive because of its light weight and excellent mechanical properties. Application of titanium materials to engine valves can reduce the inertia weight, increase the power output and improve fuel economy. Therefore, titanium materials have been adopted for racing automobile engine valves early on.

However, in terms of cost, titanium materials are not employed in mass production engine valves. In particular, the conventional titanium material has a limit of use thereof at a temperature of about 600 ° C., and it is difficult to employ a member used in a high temperature range such as an exhaust valve.

Next, the heat resistance of the titanium material is examined. In general, the heat resistance of titanium alloys is governed by the structure of the structure. The structure is determined by the alloy composition, processing temperature, workability and post-treatment heat treatment conditions. In particular, the influence of the processing temperature on the structure of the tissue is large.

For example, silicon may be contained in a titanium alloy to improve the heat resistance of the titanium material. In such a case, it is necessary to determine the processing temperature in consideration of the relationship between the β transformation point and the solid solution temperature of the silicon compound (silicide). Specifically, when the β transformation point is higher than the solubility temperature of the silicide, a titanium needle (for example, a Ti-Al-Sn-Zr-Nb-Mo-Si-based titanium alloy) is hot formed at a high temperature above the β transformation point to produce a large acicular structure. This is formed. Such needle-like structures are undesirable because they cause forging cracks, ductility deterioration, and deterioration of low cycle fatigue characteristics.

On the other hand, processing below the β transformation point is generally difficult because of the large deformation resistance. As can be seen from these examples, when the heat resistance of the titanium material is improved, the workability is lowered. Therefore, it is difficult to attain both heat resistance and workability.

In order to solve such a problem and to further improve the heat resistance and the like of the titanium material, various proposals have been made. For example, there are the following.

(1) Japanese Patent Laid-Open No. 4-56097 (Registration No. 1772182) discloses an Al-Sn-Zr-Nb-Mo-Si alloy containing a small amount of C. By adding a small amount of C, such a titanium alloy expands the α + β region, which is a temperature range of heat treatment and hot working, to improve heat resistance, heat treatment, and hot workability.

However, in the case of such a titanium alloy, the temperature (use limit temperature) at which sufficient high temperature tensile strength and fatigue characteristics are obtained is about 600 ° C. In addition, these titanium alloys are produced using melting, casting and forging as basic processes. Therefore, it is expensive and is not suitable for mass-produced products which require low cost such as automobile parts.

In addition, the α + β region is expanded, but the solid solution temperature of the silicide is lower than the β transformation point. Therefore, when hot processing is performed at a higher temperature than β transformation point, a huge needle-like structure is formed. In order to avoid this, the said publication eventually processes at the temperature below (beta) transformation point. Thus, these titanium alloys form a balanced bi-modal structure in material properties, but still have high processing resistance and insufficient hot workability.

(2) Japanese Unexamined Patent Application Publication No. Hei 4-202729 discloses an Al-Sn-Zr-Nb-Mo-Si-based alloy, in which a large amount of Mo is added. Thereby, the heat resistance of an alloy is improved to about 610 degreeC.

However, also in this case, heat resistance is insufficient similarly to the titanium alloy of Unexamined-Japanese-Patent No. 4-56097. In addition, addition of a large amount of Mo is not preferable because it causes a decrease in high temperature tensile strength.

Also disclosed is a titanium alloy containing 1% or more of C, Y, B, rare earth elements and S in total. Accordingly, heat resistance, specifically creep resistance, is improved.

However, even in such a case, sufficient creep characteristics can be obtained up to about 600 ° C. in which dislocation creep predominates, and heat resistance is insufficient. In particular, the creep characteristic is not sufficient in the high temperature range of 800 degreeC around which diffusion also begins to participate.

In any case, since melting, casting, and forging are the basic processes, they are expensive and are not suitable materials for mass production parts.

(3) Titanium-based composites incorporating titanium boride whiskers using the Ingot Matallurgy Process (IM) and Rapid Solidification Process (RS) have also been reported (Refer to Preparing Damege-Tolerant Titanium-Matrix Composites, J0M, Nov 1994, P68).

According to this document, it is said that such a titanium-based composite material obtains excellent properties in terms of strength, rigidity and heat resistance.

However, the dispersion of titanium boride whiskers is nonuniform and the high cycle fatigue characteristics in the high temperature range are low. In this high temperature range, high cycle fatigue characteristics, together with high temperature creep characteristics, are important characteristics required for materials such as exhaust valves for automobile engines. Therefore, it is not a suitable material for exhaust valves and the like. In addition, since such a titanium-based composite material is based on the melting method or the quench solidification method, the titanium composite material has a high cost.

Therefore, such a titanium-based composite material is also difficult to be used for mass production parts such as automobile parts in terms of heat resistance and cost.

(4) Japanese Unexamined Patent Publication (Kokai) No. 5-5142 discloses a titanium-based composite material composed of a matrix of titanium alloys of α-type, α-type + β-type, and β-type and 5 to 50% by volume of titanium boride solid solution. have. Such a titanium-based composite material is selected from a titanium boride solid solution, which is intrinsically difficult to react with the titanium alloy, as the reinforcing particles to improve strength, rigidity, fatigue characteristics, abrasion resistance, and heat resistance.

However, even in this case, the characteristics of the titanium-based composite material are not described in the high temperature range exceeding 610 ° C.

(5) Japanese Patent No. 2523556 discloses a titanium valve in which stem parts, billet parts and head parts are molded by optimizing hot working temperature and heat treatment temperature.

Such a titanium valve combines hot processing and heat treatment well to obtain a desired tissue configuration. This satisfies the heat resistance required for the engine valve.

However, heat resistance in the high temperature range exceeding 600 degreeC is lacking. In addition, since the stem portion where fatigue resistance is important is hot worked and formed at a temperature lower than the β transformation point, hot working is difficult due to the presence of the α phase having high deformation resistance, resulting in lack of mass productivity.

Disclosure of the Invention

The present invention has been made in view of the above circumstances. In short, an object of the present invention is to provide a titanium material excellent in hot workability, strength, creep properties, fatigue properties and wear resistance.

In particular, it is an object of the present invention to provide a conventional titanium material having excellent heat resistance in the high temperature range exceeding 610 ° C.

More specifically, it is to provide a titanium-based composite material having excellent hot workability, heat resistance, mass production, and the like and a method of manufacturing the same.

MEANS TO SOLVE THE PROBLEM The present inventors earnestly researched and solved the various systematic experiment in order to solve this subject, and came to complete this invention. In short, the present inventors aim to optimize the composition of the matrix and the occupancy of the titanium compound particles and the rare earth compound particles in a titanium-based composite material composed of a titanium alloy-based matrix and titanium compound particles and rare earth compound particles dispersed in the matrix. The inventors have invented a titanium-based composite material which is excellent in hot workability, heat resistance, and mass productivity.

That is, the titanium-based composite material of the present invention is 3.0 to 7.0% by weight of aluminum (A1), 2.0 to 6.0% by weight of tin (Sn), 2.0 to 6.0% by weight of zirconium (Zr) and 0.1 to 0.4% by weight of silicon It is characterized by having the matrix which has a titanium alloy containing (Si) and 0.1-0.5 weight% oxygen (O) as a main component, and the titanium compound particle which occupies 1-10 volume% dispersed in the said matrix.

In addition, the titanium-based composite material of the present invention is 3.0 to 7.0% by weight of aluminum (Al), 2.0 to 6.0% by weight of tin (Sn), 2.0 to 6.0% by weight of zirconium (Zr) and 0.1 to 0.4% by weight of silicon It is characterized by having the matrix which has a titanium alloy containing (Si) and 0.1-0.5 weight% of oxygen (0) as a main component, and the rare earth compound particle which occupies 3 volume% or less dispersed in the said matrix.

In addition, the titanium-based composite material of the present invention is 3.0 to 7.0% by weight of aluminum (A1), 2.0 to 6.0% by weight of tin (Sn), 2.0 to 6.0% by weight of zirconium (Zr) and 0.1 to 0.4% by weight of silicon A matrix composed mainly of a titanium alloy containing (Si) and 0.1 to 0.5% by weight of oxygen (0), a titanium compound particle occupying 1 to 10% by volume dispersed in the matrix, and occupying 3% by volume or less It is characterized by having a rare earth compound particle.

Aluminum, tin, zirconium, silicon, and oxygen contained in the matrix of the titanium-based composite material of the present invention are more preferable if all of their solid solution is dissolved in titanium to form a titanium alloy.

The titanium composite material of the present invention is excellent in hot workability. In addition, strength, creep properties, fatigue properties and abrasion resistance are excellent not only at room temperature but also in the high temperature range exceeding 610 ° C. For example, it should be noted that even in the extremely high temperature range of 800 ° C, these properties are excellent. The reason why such excellent characteristics are obtained is not necessarily clear, but is considered as follows.

Aluminum is an element which raises the β transformation point of the titanium alloy which is a matrix, and stably exists the (alpha) phase in a matrix to a high temperature range. Therefore, aluminum is an element which improves the high temperature strength of a titanium type composite material. In addition, aluminum is an element which dissolves in the (alpha) phase in a matrix and improves the high temperature strength and creep characteristic of the titanium alloy which is a matrix more.

However, if the content of aluminum is less than 3.0%, the α phase of the titanium alloy is not sufficiently stabilized in the high temperature range. In addition, the high capacity of aluminum into the α phase also becomes insufficient. Therefore, improvement of high temperature strength and creep characteristic is not very desirable. On the other hand, when the content of aluminum exceeds 7.0% by weight, Ti ₃ Al precipitates and the titanium-based composite material becomes weak.

Moreover, in order to reliably improve high temperature strength and a creep characteristic, if content of aluminum is 4.0 to 6.5 weight%, it is more suitable.

Both tin and zirconium are neutral elements but, like aluminum, stably present α phase even at high temperatures. In addition, it can be dissolved in the α phase to improve high temperature strength and creep characteristics.

If the content of tin is less than 2.0% by weight, the α phase is not sufficiently stabilized up to the high temperature range, and the high capacity of the tin into the α phase is insufficient, and improvement of the high temperature strength and creep characteristics is not so desirable. In addition, when the content of tin exceeds 6.0% by weight, the effect of improving the high-temperature strength and creep properties of the titanium alloy is saturated and the density is increased, so that it is not an effective compounding. In order to reliably improve high temperature strength and creep characteristics, when the content of tin is made 2.5 to 4.5% by weight, it is more appropriate.

If the zirconium content is less than 2.0% by weight, the α phase is not sufficiently stabilized to a high temperature range and the high capacity of the zirconium to the α phase is also insufficient. Therefore, improvement of high temperature strength and creep characteristics is not so desirable. If the content of zirconium exceeds 6.0% by weight, the effect of improving the high temperature strength and creep properties of the titanium alloy will be saturated, so that it will not be an effective compounding. In order to further improve the high temperature strength and the creep characteristics, the content of zirconium is more suitably set to 2.5 to 4.5% by weight.

Silicon is an element capable of improving creep characteristics by solid solution in titanium alloys. Conventionally, creep resistance is ensured by dissolving a large amount of silicon. However, when a titanium alloy containing a large amount of silicon is maintained at a high temperature for a long time, silicon is combined with titanium or zirconium to precipitate fine silicides, thereby lowering room temperature toughness. The titanium-based composite material of the present invention can reduce the content of silicon required to obtain sufficient creep characteristics by having titanium compound particles or rare earth compound particles that are stable even at high temperatures.

If the content of silicon is less than 0.1% by weight, the creep properties are not sufficiently improved. If the content of silicon is more than 0.4% by weight, the high temperature strength is lowered. In order to reliably improve the creep characteristic, when the content of silicon is made 0.15 to 0.4% by weight, it is more appropriate.

Oxygen is an element that raises the β transformation point of the titanium alloy to stably present the α phase in the high temperature range. In addition, it is an element that can be dissolved in the α phase to improve high temperature strength and creep strength. If the content of oxygen is less than 0.1% by weight, the α phase is not sufficiently stabilized, and the high capacity of oxygen to the α phase is also insufficient, and improvement of high temperature strength and creep characteristics is not so desirable. When the content of oxygen exceeds 0.5% by weight, the titanium-based composite material tends to be weakened. In addition, in order to stably exist an alpha phase and to reliably improve high temperature strength and creep strength, when content of oxygen is made into 0.15 to 0.4 weight%, it is further more suitable.

In the titanium-based composite material of the present invention, aluminum, tin, zirconium, silicon, and oxygen contained in the matrix are thought to exert the above excellent effect by alloying when dissolved in titanium.

On the other hand, titanium compound particles and rare earth compound particles are difficult to react with the titanium alloy and are thermodynamically stable particles for the titanium alloy. Therefore, the titanium compound particles and the rare earth compound particles can be stably present in the titanium alloy even at a high temperature range.

Here, the titanium compound particles are, for example, particles such as titanium boride, titanium carbide, titanium nitride or titanium silicide. More specifically, the titanium compound particles consist of particles such as compounds such as TiB, TiC, TiB ₂ , Ti ₂ C, TiN, titanium silicide and the like. These particles have similar properties when dispersed in a titanium based composite material. These compound particles can be used alone or in combination as a reinforcing material of the titanium-based composite material.

In addition, the rare earth compound particles are particles made of oxides or sulfides of rare earth elements such as yttrium (Y), cerium (Ce), lanthanum (La), erbium (Er) or neodymium (Nd). More specifically, the rare earth compound particles are particles made of compounds such as Y ₂ O ₃ . These particles have similar properties when dispersed in a titanium based composite material. These compound particles can be used alone or in combination as a reinforcing material of the titanium-based composite material. In addition, the titanium compound particles or the rare earth compound particles may contain alloying elements constituting the matrix.

Titanium compounds including TiB and oxides or sulfides of rare earths are compounds that can stably exist at high temperatures in titanium alloys. Only a compound that can be stably present at such a high temperature can suppress β particle growth of the titanium alloy to improve hot workability, and can also improve strength, creep properties, fatigue resistance and wear resistance at room temperature or high temperature.

For example, taking titanium boride particles (TiB) as an example, the titanium boride particles effectively act to improve high temperature strength and ductility. This is also apparent in JP-A-5-5142 and the like. Therefore, by dispersing the titanium boride particles in the matrix, it is possible to improve the strength, creep properties, fatigue properties and wear resistance of the titanium-based composite material not only in the normal temperature range but also in the high temperature range.

Here, the hot workability of the titanium-based composite material of the present invention is added. In general, when the titanium alloy is heated to the completely β region and subjected to hot working, the particle diameter of the β phase becomes large, and cracks are likely to occur during hot working, and the limit fixed ratio (the minimum when cracking occurs when fixed molding is performed). Pressure drop rate) decreases. In contrast, the titanium-based composite material of the present invention has the following excellent features.

Titanium compound particles and rare earth compound particles are finely and uniformly dispersed throughout the matrix, so that during the hot working, the titanium compound particles or rare earth compound particles effectively suppress the enlargement of the crystal grain diameter of the β phase contained in the matrix (particle growth). do. Therefore, even if the titanium-based composite material of the present invention is subjected to hot working at a temperature equal to or more than the β transformation point, cracking does not occur and excellent hot workability is obtained.

In particular, when the titanium-based composite material of the present invention is obtained by the sintering method, the titanium compound particles and the rare earth compound particles are convenient because they are finely and uniformly dispersed in the matrix. In addition, since titanium compound particles and rare earth compound particles are hardly precipitated at the particle interface, the titanium-based composite material of the present invention has further excellent hot workability.

Of course, the manufacturing method of the titanium-based composite material of the present invention is not limited thereto. For example, there are a melt casting method and a quench solidification method. However, if the sintering method is used, it is excellent in all aspects such as cost, productivity and material properties.

As described above, in the titanium composite material, the titanium compound particles and the rare earth compound particles are preferably dispersed uniformly. Therefore, in the case where the titanium compound particles are dispersed in the matrix, it is necessary to occupy 1 to 10% by volume of the titanium compound particles when the volume of the entire titanium-based composite material is set to 100% by volume.

If the occupancy of the titanium compound particles is less than 1% by volume, the occupancy of the titanium compound particles is too small, and thus the titanium-based composite material does not have sufficient high temperature strength, creep properties, fatigue properties and abrasion resistance. On the other hand, when it exceeds 10% by volume, its toughness deteriorates.

When the rare earth compound particles are dispersed in the matrix, it is necessary to occupy 3% by volume of the rare earth compound particles when the volume of the entire titanium-based composite material is set to 100% by volume. It is because toughness deteriorates when it exceeds 3 volume%.

Therefore, in the titanium-based composite material of the present invention, the volume occupancy of the titanium compound particles or the rare earth compound particles is set to 1 to 10% by volume or 3% by volume or less, respectively. Accordingly, the titanium-based composite material of the present invention can sufficiently improve high temperature strength, rigidity, fatigue characteristics, abrasion resistance, and heat resistance without deteriorating toughness.

Moreover, in order to improve these characteristics further, it is more preferable to make 3-7 volume% of titanium compound particle or 0.5-2 volume% of rare earth compound particle | grains.

As described above, in the titanium-based composite material of the present invention, excellent properties are obtained with respect to strength, creep properties, high cycle fatigue properties and wear resistance along with hot workability. In particular, these characteristics are excellent also in the high temperature range exceeding 610 degreeC.

The present invention relates to a titanium-based composite material that can be used for high strength members of various machines, and a method for producing the same. Specifically, the present invention relates to a titanium-based composite material suitable for a member requiring heat resistance, such as an engine valve such as an automobile, and a manufacturing method thereof.

1 is a structure of an engine valve of Sample 5 of Example 4 taken with an optical microscope.

FIG. 2 is a TEM diagram showing one example of titanium boride particles contained in the titanium composite material of the present invention and the shape of an interface between a matrix (titanium alloy) and titanium boride particles.

FIG. 3 is a TEM (Transmission E1ectron Microscope) diagram showing an enlarged shape of an interface between a matrix (titanium alloy) and titanium boride particles of the titanium-based composite material of the present invention.

4 is a graph showing creep characteristics (relationship between elapsed time and creep flexibility) at 800 ° C for the samples of Example (Sample 3) and Comparative Example (Sample C6).

It is a figure which shows the shape of the valve molded object produced in Example 1. FIG.

It is a figure which shows the shape of the engine valve produced in Example 1. FIG.

Best Mode for Carrying Out the Invention

(Titanium composite material)

In the titanium composite material of the present invention, when the titanium alloy which is the main component of the matrix is 100% by weight of the whole titanium-based composite material, 0.5 to 4.0% by weight of molybdenum (Mo) and 0.5 to 4.0% by weight of niobium ( It is further more suitable if it contains Nb).

Molybdenum is an element that effectively stabilizes the β phase of the titanium alloy. In particular, when the titanium-based composite material of the present invention is obtained by sintering, molybdenum has a function of finely depositing α phase in the cooling process after sintering. In short, molybdenum further improves the strength in the mid-low temperature range of the titanium-based composite material, and in particular, further improves its fatigue properties.

However, if the content of molybdenum is less than 0.5% by weight, it is difficult to sufficiently improve the strength of the titanium-based composite material. On the other hand, when content of molybdenum exceeds 4.0 weight%, (beta) phase will increase and the high temperature strength, creep characteristic, and toughness of a titanium-type composite material will fall. Further, in order to reliably improve the strength, fatigue characteristics, high temperature strength, creep characteristics, and toughness in the mid-low temperature range, the content of molybdenum is further suited to 0.5 to 2.5% by weight.

Next, niobium is also an element that effectively stabilizes the β phase similarly to molybdenum. If the content of niobium is less than 0.5% by weight, the high temperature strength does not sufficiently improve. Moreover, when content of niobium exceeds 4.0 weight%, (beta) phase will increase and high temperature strength, creep characteristic, and toughness will fall. In addition, in order to reliably improve high temperature strength, creep characteristics, and toughness, the content of niobium is further suitably set to 0.5 to 1.5% by weight.

In addition, molybdenum and niobium are both elements which suppress the precipitation of Ti ₃ Al. Therefore, when these elements are contained in the titanium alloy, the fragility in the high temperature range of the titanium-based composite material can be prevented even when aluminum, tin and zirconium are contained in the titanium alloy. In addition, the high temperature strength and the ductility of the titanium-based composite material are improved in a balanced manner, and the oxidation resistance thereof is also improved.

In addition, the titanium alloy which is a main component of the matrix of the titanium-based composite material of the present invention is suitably further contained at least 5% by weight in total of at least one metal element of tantalum (Ta), tungsten (W) and hafnium (Hf). .

Tantalum is a β stabilizing element. The appropriate amount of tantalum improves the balance between high temperature strength and fatigue strength of titanium-based composite materials. When the titanium-based composite material contains tantalum more than necessary, its density increases, and its β phase increases, thereby reducing its high temperature creep strength.

Tungsten is also a β stabilizing element. The appropriate amount of tungsten improves the balance between high temperature strength and fatigue strength of titanium-based composite materials. When the titanium-based composite material contains tantalum more than necessary, its density increases, and its β phase increases, thereby reducing its high temperature creep strength.

Hafnium is a neutral element and has the same action and effect as zirconium. In short, an appropriate amount of hafnium is dissolved in the α phase to improve the high temperature strength and creep properties of the titanium-based composite material. If the titanium-based composite material contains hafnium more than necessary, its density rises and is not preferable.

These elements are elements which are preferably contained in the matrix additionally. Therefore, in order to make the density of the titanium-based composite material not too large while utilizing the inherent properties of the matrix, the total amount thereof is preferably 5% by weight or less.

Further, the titanium compound particles and the rare earth compound particles contained in the titanium composite material of the present invention are more suitable if the average aspect ratio is 1 to 40 and the average particle diameter is 0.5 to 50 µm.

Here, an average aspect ratio means the value which measured the long diameter D1 and the short diameter D2 of each particle, and averaged the ratio (D1 / D2) to all the particle | grains to be measured. In addition, an average particle diameter means the value which averaged the diameter at the time of showing the cross-sectional shape of each particle by the circle equivalent to an area to all the particle | grains to be measured. In addition, the number of particle | grains to be measured at this time shall be 500-600 pieces.

The hot workability of the titanium-based composite material of the present invention can be further improved by setting the average aspect ratio of the titanium compound particles or the rare earth compound particles to 1 to 40 and the average particle diameter to 0.5 to 50 µm. In addition, its high temperature strength, creep properties, fatigue properties and wear resistance can be improved.

The reason is not necessarily clear, but it is thought as follows. Here, the reason will be explained using titanium boride particles as an example.

The mismatch at the interface between the titanium boride particles and the titanium alloy is at most 2.2% as shown in FIGS. 2 and 3. In short, the matchability at its interface is very high. Therefore, the interfacial energy between the titanium boride particles and the titanium alloy is small, and it is difficult for the small titanium boride particles to grow particles in the titanium alloy even at high temperature, for example. Therefore, even in the high temperature range, the interfacial structure between the titanium boride particles and the titanium alloy does not change, and the titanium-based composite material exhibits high strength.

However, when the average particle diameter of the titanium boride particles is less than 0.5 µm, such an effect is not sufficiently obtained. In addition, when the average particle diameter exceeds 50 µm, the particle distribution thereof becomes non-uniform, and the particles cannot make the stress sharing uniform. Therefore, the titanium-based composite material will proceed from the weak matrix.

In addition, if its average aspect ratio exceeds 40, it causes non-uniformity of its particle distribution. Therefore, the particles can not evenly share the stress and proceed from the part of the matrix where the destruction of the titanium-based composite material is vulnerable. As the average aspect ratio approaches 1, the titanium boride particles become spherical and the particles are uniformly dispersed, which is preferable.

As described above, titanium boride particles have been described as examples, but other titanium compound particles and rare earth compound particles such as titanium boride particles, titanium carbide particles, titanium nitride particles or titanium silicide particles, yttrium (Y), cerium (Ce), The same applies to particles mainly composed of oxides or sulfides of lanthanum (La), erbium (Er) or neodymium (Nd).

Therefore, if the average aspect ratio of the titanium compound particles or the rare earth compound particles is 1 to 40 and the average particle diameter is 0.5 to 50 µm, a titanium-based composite material obtained by dispersing a large amount of the fine titanium compound particles and the rare earth compound particles in a large amount and uniformly is obtained. The titanium composite material thus obtained has excellent properties in high temperature strength, creep properties, fatigue properties and wear resistance.

Further, when the average aspect ratio of the titanium compound particles or the rare earth compound particles is set to 1 to 20 and the average particle diameter is set to 0.5 to 30 μm, these particles are more uniformly dispersed and the properties of the titanium-based composite material are further improved. More preferred.

Moreover, it is preferable that the titanium alloy which is a matrix of the titanium-type composite material of this invention consists of a beta phase and the needle-shaped alpha phase which precipitated from the beta phase.

By depositing such acicular α-phase from the β-phase, the high temperature creep characteristic of the titanium-based composite material can be improved.

(Method for producing titanium composite material)

The manufacturing method for obtaining the titanium-based composite material of the present invention thus excellent is not particularly limited. Here, as an example of the production method thereof, another method of manufacturing the titanium-based composite material will be described.

This manufacturing method is a particularly suitable manufacturing method for producing the titanium-based composite material of the present invention.

MEANS TO SOLVE THE PROBLEM The present inventors earnestly researched and tried to establish the manufacturing method of a titanium type composite material suitable for obtaining the said excellent titanium type composite material. And the present inventors came up with using sintering as a manufacturing method of the titanium type composite material of this invention. Next, the raw material, the shaping | molding and sintering method, its sintering temperature, etc. were repeated and examined. As a result, the present inventors confirmed that the titanium-based composite material obtained by sintering at a temperature above β transformation point to generate α phase and β phase in the matrix is not only excellent in hot workability but also in strength, creep property, fatigue property and wear resistance. did. In addition, the present inventors have found that such a titanium-based composite material is excellent in such characteristics at room temperature as well as at a high temperature exceeding 610 ° C.

The method for producing the titanium-based composite material of the present invention is made based on this finding.

That is, the method for producing a titanium-based composite material of the present invention is 3.0 to 7.0% by weight of aluminum, 2.0 to 6.0% by weight of tin, 2.0 to 6.0% by weight of zirconium, 0.1 to 0.4% by weight of silicon and 0.1 to 0.5% by weight Titanium-based composite material having a matrix composed mainly of a titanium alloy containing oxygen, and titanium compound particles occupying 1 to 10% by volume dispersed in the matrix and / or rare earth compound particles occupying 3% by volume or less. Mixing process for producing titanium powder, alloy urea powder containing aluminum, tin, zirconium, silicon and oxygen and particle urea powder forming titanium compound particles and / or rare earth compound particles, mixing obtained in the mixing process A molding step of molding a molded article having a predetermined shape using powder, and sintering the molded article obtained in the molding step at a temperature of β transformation point or more. Sintering process to produce a β-phase, and it has a cooling step for depositing the α phase from said β phase.

The method for producing a titanium-based composite material of the present invention comprises a series of processes of mixing, forming, sintering and cooling. Each process can be carried out as follows.

(1) mixing process

The mixing process first produces titanium powder, alloy urea powder containing aluminum, tin, zirconium, silicon and oxygen, and particle urea powder forming titanium compound particles and / or rare earth compound particles.

① titanium powder

As the titanium powder, for example, powders such as sponge titanium powder, hydrogenated dehydrogen powder, titanium hydride powder and atomized powder can be used. The shape, particle diameter (particle diameter distribution), and the like of the constituent particles of the titanium powder are not particularly limited. Commercially available titanium powder is adjusted to about 150 μm (# 100) or less and about 100 μm or less by an average particle diameter, and thus can be used as it is. In addition, when the particle diameter of the titanium powder is 45 μm (# 325) or less and an average particle diameter of about 20 μm or less is used, it is easy to obtain a dense sintered body.

In addition, it is preferable that the average particle diameter of a titanium powder is 10-200 micrometers from a viewpoint of cost and the compactness of a sintered compact.

② alloy element powder

Alloy urea powder is necessary to obtain titanium alloy, which is the main component of the matrix

Powder. These titanium alloys contain aluminum, tin, zirconium, silicon and oxygen in addition to titanium, so that the alloying element powders may be made of, for example, aluminum, tin, zirconium, silicon alone (metal body) or aluminum, tin, zirconium, silicon and oxygen. It consists of a compound, alloy powder, etc. The powder of an alloy or a compound which can be manufactured by one or a combination of these elements may be sufficient. Moreover, the powder of the alloy and compound which can be manufactured by titanium or one or each combination of these elements may be sufficient. The composition of the alloy urea powder is appropriately prepared according to the blending amount of the matrix.

In addition, an alloy powder containing all of aluminum, tin, zirconium, silicon, and oxygen can be produced as an alloy element powder. In addition, it is good also as an alloy element powder combining the powder of a compound and the powder of a metal (single or an alloy). For example, it is good also as an alloying element powder, combining the compound powder of aluminum, and the alloy powder which consists of tin, zirconium, silicon, and oxygen.

③ particle urea powder

Particle urea powder is necessary for forming titanium compound particles or rare earth compound particles. The particle urea powder may be a powder of the titanium compound or the rare earth compound itself. It may also be a powder of boron, carbon, nitrogen, silicon or the like, a single element, an alloy, or a compound of titanium compound particles or rare earth compound particles which react with the constituent elements of the matrix (titanium, oxygen, etc.) to form titanium compound particles or rare earth compound particles. It may also be a combination of these various powders.

Here, the titanium compound particles include titanium boride particles, titanium carbide particles, titanium nitride particles or titanium silicide particles. The titanium compound particles may be one of these as well as combinations thereof. The rare earth compound particles include oxides or sulfides of yttrium (Y), cerium (Ce), lanthanum (La), erbium (Er) or neodymium (Nd). The rare earth compound particles may be one of these as well as combinations thereof. Further, the powder of the titanium compound particles and the powder of the rare earth compound particles may be combined to form a particle urea powder.

Herein, a representative titanium boride powder will be described as an example of the particle urea powder. Titanium boride powder contains titanium boride (TiB ₂ etc.) as a main component. Such titanium boride powder may contain an alloying element of the matrix. For example, the titanium boride powder may be made of a powder of aluminum, tin, zirconium, silicon or oxygen, powder such as alloy, and powder of boron compound, alloy.

Boron in the titanium boride powder reacts with titanium to form titanium boride particles in the following sintering process. In addition, if there is an alloy or a compound containing boron in the alloy element powder, it is convenient because there is no need to separately prepare the titanium boride powder.

The shape and particle diameter (particle diameter distribution) of the particles constituting the alloy urea powder and the particle urea powder are not particularly limited, but the average particle diameter of the alloy urea powder is 5 to 200 µm and the average particle diameter of the particle urea powder is 1. If it is 30 micrometers, the titanium type composite material which has a uniform structure will be obtained, and it is more suitable.

When obtaining powder of relatively large particle diameter, it is good to adjust it by grind | pulverizing to a desired particle size with various grinders, such as a ball mill, a vibration mill, and an attritor.

④ mixed

The titanium powder, alloy urea powder, and particle urea powder thus prepared are mixed. This mixing method may be mixed using a V-type mixer, a ball mill, a vibration mill, or the like, but is not particularly limited thereto. In this step, a well-known mixing method can be employed to obtain a mixed powder in which each powder particle is uniformly dispersed without taking any special means. Therefore, this process can be achieved very cheaply.

However, when alloy urea powder or particle urea powder is a particle which violently aggregates secondary particles, etc., it is preferable to carry out stirring-mixing process in an inert gas atmosphere using high energy ball mills, such as an atomizer. By carrying out such treatment, the titanium-based composite material can be made more compact.

(2) forming process

A molding process is a process of shape | molding the molded object of a predetermined shape using the mixed powder obtained by said mixing process. This predetermined shape may be the final shape of the target object, and may be a billet shape when processing is performed after the sintering process.

As a shaping | molding method in such a shaping | molding process, methods, such as die shaping | molding, CIP shaping | molding (cold hydrostatic pressure press molding), RIP shaping | molding (rubber hydrostatic pressure press molding), etc. can be used, for example. Of course, it is not limited to these and other well-known powder shaping | molding methods can be used. Moreover, when using methods, such as metal mold shaping | molding, CIP shaping | molding, and RIP shaping | molding, it is good to adjust these shaping | molding pressures etc. so that a desired mechanical property may be obtained.

(3) sintering process

A sintering process is a process of sintering the molded object obtained by the molding process to the temperature more than (beta) transformation point of a matrix. In short, each particle in contact with the molded body is sintered by the sintering step. When sintering in this way, the following occurs.

When the molded body is heated above the β transformation point, the titanium powder and the alloy element powder are alloyed to form a titanium alloy as a matrix. At the same time, particles of a novel compound (such as TiB) are formed between the titanium powder and the particle urea powder.

By sintering such a molded body, a titanium-based composite material in which titanium compound particles and / or rare earth compound particles are dispersed in a matrix mainly composed of a titanium alloy is formed.

Sintering in the sintering step is preferably performed in a vacuum or inert gas atmosphere. Moreover, although sintering temperature is implemented in the temperature range more than (beta) transformation point, it is more preferable if such temperature range is 1200 degreeC-1400 degreeC. In addition, the sintering time thereof is preferably 2 to 16 hours. Densification is not always sufficient for sintering below 1200 ° C. and below 2 hours. Temperatures above 1400 ° C. or sintering for more than 16 hours are uneconomical in energy and inefficient in terms of productivity.

Therefore, it is preferable to carry out the sintering under the sintering conditions of 1200 to 1400 ° C. for 2 to 16 hours to obtain a titanium-based composite material having a desired structure.

In addition, the above-described production method can be used when the titanium alloy as the main component of the matrix contains niobium, molybdenum, tantalum, tungsten and hafnium in addition to aluminum, tin, zirconium, silicon and oxygen.

In short, a powder containing these various elements is prepared in advance and this powder is used as the alloying element powder in the mixing step. In this way, niobium, molybdenum, tantalum, tungsten and hafnium can be easily contained in the matrix. In this case as well, if a single element (metal), alloy, or compound powder of each element of aluminum, tin, zirconium, silicon, oxygen, niobium, molybdenum, tantalum, tungsten and hafnium is produced so as to contain a predetermined amount Good.

In addition, when titanium oxide particles having an average aspect ratio of 1 to 40 and an average particle diameter of 0.5 to 50 µm or particle urea powders containing rare earth compound particles are mixed and sintered, these titanium compound particles and / or are easily formed by solid phase reaction. The rare earth compound particles can be uniformly dispersed in the matrix.

(4) cooling process

The cooling step is a step of depositing a needle-like α phase from the β phase after the sintering step. By finely dispersing the α phase in the β phase, that is, the strength of the titanium-based composite material can be remarkably improved by precipitation strengthening.

Specifically, the needle-like α phase can be precipitated from the β phase by cooling at a desired cooling rate after sintering. This cooling rate is preferably 0.1 to 10 ° C / s. In particular, it is more preferable if the cooling rate is about 1 ° C / s. Further, such cooling methods include furnace cooling, controlled cooling, and the like. Controlled cooling includes forced cooling by inert gas such as argon gas, cooling by controlling the voltage of the furnace, and the like, and the cooling rate is adjusted by these.

Here, a titanium-based composite material using titanium compound powder (a kind of particle urea powder) containing titanium boride (TiB ₂ ) will be taken as an example, and a cooling process will be described. After the sintering step, the two-phase structure of the β phase of the titanium alloy and the TiB particles (titanium compound particles) is obtained. When this is cooled at the above-mentioned cooling rate, needle-like α phase is precipitated from such β phase.

As a result, a mixed phase of the β phase and the needle-like α phase is formed. The mixed phase of the β-phase, acicular-phase α-phase and TiB particles improves the creep and fatigue properties of the titanium-based composite material in the high temperature range. In addition, such TiB particles effectively suppress the enlargement of the particle diameter of the β-phase when the titanium-based composite material is hot worked.

The above process can use the raw material powder and existing equipment which are easy to obtain. In addition, the number of processes is small and each process is simple. Therefore, this manufacturing method is particularly suitable for obtaining the titanium-based composite material of the present invention.

Conventionally, it is very difficult to obtain a titanium material excellent in hot workability, high temperature strength, creep properties, fatigue properties, and wear resistance. Therefore, the productivity of such titanium materials is extremely poor and its use is limited to special fields.

As described above, the titanium-based composite material of the present invention and the production method thereof solve the present problem excellently.

Example of adaptation of this manufacturing method

It has been described first that the titanium-based composite material of the present invention is suitable for automobile engine valves. Such automotive engine valves can be easily manufactured using the method for producing a titanium-based composite material of the present invention. In such a case, when the molded body is molded into a desired valve shape in the molding step, the production of the engine valve for an automobile is further facilitated.

Next, the production of the engine valve for automobiles will be taken as an example, and the method for producing the titanium-based composite material of the present invention will be described in detail.

① Form billet of proper shape in molding process. Next, the molded body is sintered in the sintering step. And the hot work process which hot-processes the obtained sintered compact to a valve shape at the temperature more than (alpha) + (beta) area | region or (beta) transformation point is added.

The sintered body obtained by the method for producing a titanium-based composite material of the present invention has a mixed phase of titanium compound particles and / or rare earth compound particles such as β-phase and needle-shaped α-phase and TiB particles. Accordingly, even when hot working at a temperature above the α + β range or β transformation point, the deformation resistance is low and the hot workability is excellent. In such a case, since hot working can be easily performed using existing hot working facilities, it is preferable.

The reason why such a sintered body has good hot workability is that abnormal grain growth of β particles is suppressed by TiB particles or the like even when heated above the β transformation point (specifically, the average particle diameter can be adjusted to 50 μm or less). This is because hot working can be performed at a β transformation point or more. In other words, since the hot working can be performed at the β transformation point or more, a healthy working material is obtained in which the deformation resistance during processing is small, there is no abnormal grain growth of the β particles, and there are no wrinkles or cracks.

(2) It is more preferable if the following is performed among these hot working processes.

First, the sintered compact is hot-extruded at a temperature equal to or higher than α + β or a β transformation point to form a stem portion having a desired shape. Next, the head part of a desired shape is shape | molded by hot forging in the temperature more than (alpha) + (beta) area | region or (beta) transformation point. At this time, the stem part and the head part may be integrally processed to form an engine valve material, or the stem part and the head part may be joined by welding or the like to form an engine valve material. Next, the material may be finished to form an engine valve having a desired means.

At this time, it is preferable that both the processing temperatures are in the range of 900 ° C to 1200 ° C at the time of molding the stem and the head. It is because it is difficult to make deformation resistance small enough if its processing temperature is less than 900 degreeC. On the other hand, if its processing temperature exceeds 1200 ° C., oxidation is severe and there is a possibility that it will adversely affect the material properties or fine cracks on the surface during hot working.

(3) In addition, when the shape of the molded body is brought closer to the desired valve shape in the molding step, the hot working of the sintered body becomes easier, which is preferable. As such, the present production method is particularly suitable for the production of engine valves made of the titanium-based composite material of the present invention. In addition, it is possible to mass-produce engine valves having excellent high temperature strength, specific strength, and the like, and such engine valves can be obtained at low cost. In particular, an engine valve made of the titanium-based composite material of the present invention is excellent in that it has heat resistance.

The present invention will be described in detail with reference to specific examples and comparative examples.

Example 1 Sample 1

(1) An alloy element powder composed of a commercially available hydrogenated dehydrogenated titanium powder (# 100) and an alloy powder having a composition of 42.1 Al-28.4 Sn-27.8 Zr-1.7 Si [average particle diameter: 9 μm; % (The same applies hereinafter)] and TiB ₂ powder (average particle diameter: 2 μm) which are particle urea powders, respectively. In addition, the amount of oxygen in the matrix is adjusted by appropriately selecting and using titanium powders having different amounts of oxygen. This is also the same in each of the following Examples and Comparative Examples. In this connection, titanium powder containing 0.1 to 0.35% by weight of oxygen was used, but some oxygen was contained in the alloy element powder (about 0.1% by weight).

These raw material powders are mix | blended in arbitrary ratios, and it mixes well with an ato writer (mixing process). The mixed powder thus obtained is used to mold a billet (? 16 × 32 mm) of billet by mold molding (molding step). The molding pressure here is 6 t / cm 2.

The billet was then heated in a vacuum of 1 × 10 ⁻⁵ Torr to raise the sintering temperature from room temperature to a sintering temperature of 1300 ° C. at a heating rate of 12.5 ° C./min (the same as in Examples and Comparative Examples below). Hold for a time and sinter (sintering process). Next, it cools at the cooling rate of 1 degree-C / s (cooling process).

The sample for measurement (sample 1) used in the following measurement is obtained from the sintered compact thus obtained.

Sample 1 was measured using a scanning electron microscope (SEM) and a wet analyzer to measure the composition of the matrix and the occupancy of titanium boride particles (TiB particles). Table 1 shows the results of these measurements.

In addition, content of each element of aluminum, tin, zirconium, silicon, oxygen, niobium, and molybdenum shown in Table 1 is a value when the weight of the whole sample is 100 weight%, and the occupancy amount of the titanium boride particle | grains is the volume of the whole sample. This value is 100 vol%. This point is also the same in the following Examples and Comparative Examples.

Moreover, as a result of measuring the relative density with respect to the true density of the sample 1 by the Archimedes method, it turned out that the relative density is 98.5%. From this point, it was found that Sample 1 was excellent in compactness.

(2) On the other hand, the above-mentioned mixed powder is used to produce a valve as follows.

The mixed powder is CIP-molded at 4 t / cm 2 to obtain a valve molded body having a shape of 8 mm (stem diameter) x 35 mm (head diameter) x 120 mm (full length). The shape of such valve shaping is shown in Fig. 5A. Subsequently, such a valve-shaped molded body is subjected to sintering and cooling for 16 hours at 1300 ° C. in a vacuum of 1 × 10 ⁻⁵ Torr. And this sintered compact is finished to a desired shape, and an engine valve is obtained. The shape of such an engine valve is shown in FIG. 5B. Such engine valves are subjected to practical endurance tests and evaluated.

Example 2: Sample 2

(1) an alloy element powder (average particle diameter: 9 mu m) consisting of a commercially available sponge titanium powder (# 100), an alloy powder having a composition of 36.9 Al-24.9 Sn-24.4 Zr-6.2 Nb-6.2 Mo-1.4 Si; TiB ₂ powder (average particle diameter: 2 μm), which is particle urea powder, was prepared, respectively. Each of these raw powders is blended in an arbitrary ratio and mixed well using an AtoWriter (mixing step). Using the mixed powder thus obtained, a molded article having a predetermined shape is formed by CIP molding (molding step). Here, the molding pressure is 4 t / cm 2.

Subsequently, the molded body is heated in a vacuum of 1 × 10 ⁻⁵ Torr to raise the temperature from room temperature to a sintering temperature of 1300 ° C. at the above-mentioned temperature rising rate of 12.5 ° C./min, and hold at this sintering temperature for 16 hours for sintering (sintering process ). Next, it cools at the cooling rate of 1 degree-C / s mentioned above (cooling process). The measurement sample (sample 2) used in the following measurement is obtained from the sintered compact obtained in this way.

With respect to Sample 2, the composition of the matrix and the occupancy of the titanium boride particles were measured in the same manner as in Example 1. Table 1 shows the results of these measurements.

In addition, the relative density with respect to the true density of the sample 2 was measured like Example 1, and the relative density is 98.5%. From this point of view, it was found that Sample 2 was also excellent in compactness.

(2) On the other hand, a valve is manufactured in the same manner as in Example 1 using the above-described mixed powder.

Example 3: Sample 3

① Raw material powder, alloy element powder (average particle diameter: 9 micrometers) which consists of a commercially available hydrogenated dehydrogenated titanium powder (# 100) and the alloy powder which has a composition of 36.9 Al-24.9 Sn-24.4 Zr-6.2 Nb-6.2 Mo-1.4 Si. And TiB ₂ powder (average particle diameter: 2 m), which are particle urea powders, are prepared, respectively. These raw material powders are mix | blended in arbitrary ratios, and it mixes well with an ato writer (mixing process). The mixed powder thus obtained is used to mold a billet (? 16 × 32 mm) of billet by mold molding (molding step). Here, the molding pressure is 6 t / cm 2.

This billet is then heated in a vacuum of 1 × 10 ⁻⁵ Torr to a sintering temperature from room temperature to a sintering temperature of 1300 ° C. at a heating rate of 12.5 ° C./min as described above, and maintained at this sintering temperature for 4 hours (sintering step). . Next, it cools at the cooling rate of 1 degree-C / s mentioned above (cooling process). The measurement sample (sample 3) used in the following measurement is obtained from the sintered compact obtained in this way.

About sample 3, it carried out similarly to Example 1, and measures the composition of a matrix and the occupancy amount of the titanium boride particle | grains. Table 1 shows the results of these measurements.

In addition, the relative density with respect to the true density of the sample 3 was measured like Example 1, and the relative density is 98.5%. From this point, it was found that Sample 3 was also excellent in compactness.

(2) On the other hand, a valve is manufactured in the same manner as in Example 1 using the above mixed powder.

Example 4: Samples 4-9

① Raw material powder, alloy element powder (average particle diameter: 9 micrometers) which consists of a commercially available hydrogenated dehydrogenated titanium powder (# 100) and the alloy powder which has a composition of 36.9 Al-24.9 Sn-24.4 Zr-6.2 Nb-6.2 Mo-1.4 Si. And TiB ₂ powder (average particle diameter: 2 m), which are particle urea powders, are prepared, respectively. These raw material powders are each blended in an arbitrary ratio and mixed well by an AtoWriter (mixing process).

In addition, in this example, six types of mixed powders having different blending ratios are prepared. The six types of mixed powders thus obtained are used separately, and six types of cylindrical bodies (? 16x32) made of each mixed powder are formed by mold molding (molding step). Here, the molding pressures are all 6t / cm 2.

Subsequently, these molded bodies are heated in a vacuum of 1 × 10 ⁻⁵ Torr to raise the sintering temperature from room temperature to a sintering temperature of 1300 ° C. at the above-mentioned temperature rising rate of 12.5 ° C./min and hold at this sintering temperature for 4 hours (sintering step). Next, it cools at the cooling rate of 1 degree-C / s mentioned above (cooling process). From each of the sintered billets thus obtained, samples for measurement (samples 4 to 9) used in the following measurements are obtained, respectively.

With respect to Samples 4 to 9, the composition of the matrix of each sample and the occupancy of the titanium boride particles were measured in the same manner as in Example 1. These measurement results are shown in Table 1, respectively. In Sample 5, it was found that the average aspect ratio of the titanium boride particles was 35, and the average particle diameter was 2 m.

In addition, the relative density with respect to the true density of the samples 4-9 was measured respectively similarly to Example 1, and as a result, both samples are 98.5% of the relative density. From this point of view, it was found that Samples 4 to 9 were also excellent in compactness.

(2) The stem portions are formed by hot extrusion at 1150 ° C using the respective sintered billets of samples 5 and 9 described above. Subsequently, the remaining portions are heated to 1150 ° C. to mold the head portions by forging. Such a valve molded body has the same shape as the valve molded body of Example 1 shown in FIG. 5A.

The cross-sectional structure in the extrusion direction thereof is shown in FIG. 1 for the stem portion of the engine valve made of the sintered billet from which Sample 5 was obtained. From FIG. 1, it was found that such a tissue exhibits a structure in which titanium boride particles are oriented in the extrusion direction in the α + β phase of the matrix.

Example 5: Sample 10

① raw material powders, commercially available hydrogenated dehydrogenated titanium powder (# 100), alloy element powder (average particle diameter: 3 μm) and particle element composed of alloy powder having a composition of 33.0 Al-22.0 Sn-22.0 Zr-22.0 Mo-1.0 Si TiB ₂ powder (average particle diameter: 2 μm), which is a powder, was prepared, respectively. These raw powders are each blended in an arbitrary ratio and mixed well to obtain a mixed powder (mixing step). Such mixed powder is molded into a cylindrical shape (ø16 × 32) by mold molding (molding step). Here, the molding pressure is 6 t / cm 2.

Subsequently, the molded body is heated in a vacuum of 1 × 10 ⁻⁵ Torr to a sintering temperature of 1300 ° C. from room temperature at the above temperature increase rate of 12.5 ° C./min, and maintained at this sintering temperature for 4 hours for sintering (sintering fair). Next, it cools at the cooling rate of 1 degree-C / s mentioned above (cooling process). The sample for measurement (sample 10) used in the following measurement is obtained from the sintered compact thus obtained.

About sample 10, it carried out similarly to Example 1, and measures the composition of a matrix and the occupancy amount of the titanium boride particle | grains. The measurement results thereof are shown in Table 1.

In addition, the relative density with respect to the true density of the sample 10 was measured like Example 1, and the relative density is 98.5%. From this point, it was found that Sample 10 was also excellent in compactness.

② The stem is molded by hot extrusion at 1150 ° C. using the sintered body described above.

Example 6: Sample 11

① Raw material powder, alloy element powder (average particle diameter: 9 micrometers) which consists of a commercially available hydrogenated dehydrogenated titanium powder (# 100) and the alloy powder which has a composition of 36.9 Al-24.9 Sn-24.4 Zr-6.2 Nb-6.2 Mo-1.4 Si. And TiC powder (average particle diameter: 3 µm), which are particle urea powders, are prepared, respectively. These raw powders are each blended in an arbitrary ratio and mixed well to obtain a mixed powder (mixing step). Such mixed powder is molded into a cylindrical shape (ø16 × 32) by mold molding (molding step). Here, the molding pressure is 6 t / cm 2.

Subsequently, the molded body is heated in a vacuum of 1 × 10 ⁻⁵ Torr to raise the sintering temperature from room temperature to a sintering temperature of 1300 ° C. at a heating rate of 12.5 ° C./min as described above, and to sinter by holding at this sintering temperature for 4 hours (sintering step) ). Next, it cools at the cooling rate of 1 degree-C / s mentioned above (cooling process). The measurement sample (sample 11) used in the following measurement is obtained from the sintered compact obtained in this way.

About the sample 11, it carried out similarly to Example 1, and measures the composition of a matrix and the occupancy amount of titanium carbide particle (TiC). The measurement results thereof are shown in Table 1.

In addition, the relative density with respect to the true density of the sample 11 was measured like Example 1, and the relative density is 98.5%. From this point of view, it was found that Sample 11 was also excellent in compactness.

(2) An engine valve was produced by the same method as Sample 5 of Example 4 using the sintered body described above, and this was provided to the endurance test.

Example 7: Sample 12

① Raw material powder, alloy element powder (average particle diameter: 9 micrometers) which consists of a commercially available hydrogenated dehydrogenated titanium powder (# 100) and the alloy powder which has a composition of 36.9 Al-24.9 Sn-24.4 Zr-6.2 Nb-6.2 Mo-1.4 Si. And TiC powder (average particle diameter: 3 µm) and TiB ₂ powder (average particle diameter: 3 µm) as particle urea powders, respectively. These raw powders are each blended in an arbitrary ratio and mixed well to obtain a mixed powder (mixing step). Such mixed powder is molded into a cylindrical shape (ø16 × 32) by mold molding (molding step). Here, the molding pressure is 6 t / cm 2.

Subsequently, the molded body is heated in a vacuum of 1 × 10 ⁻⁵ Torr to a sintering temperature of 1300 ° C. from room temperature at the above temperature increase rate of 12.5 ° C./min, and maintained at this sintering temperature for 4 hours for sintering (sintering fair). Next, it cools at the cooling rate of 1 degree-C / s mentioned above (cooling process). The measurement sample (sample 12) used in the following measurement is obtained from the sintered compact obtained in this way.

About the sample 12, it carried out similarly to Example 1, and measures the composition of a matrix, and the occupancy amount of the titanium carbide particle and titanium boride particle | grains. The measurement results thereof are shown in Table 1.

In addition, the relative density with respect to the true density of the sample 12 was measured like Example 1, and the relative density is 98.5%. From this point of view, it was found that Sample 12 was also excellent in compactness.

(2) The stem portion is molded by hot extrusion at 1150 占 폚 using the sintered body described above.

Example 8: Sample 13

① Raw material powder, alloy element powder (average particle diameter: 9 micrometers) which consists of a commercially available hydrogenated dehydrogenated titanium powder (# 100) and the alloy powder which has a composition of 36.9 Al-24.9 Sn-24.4 Zr-6.2 Nb-6.2 Mo-1.4 Si. And TiB ₂ powder (average particle diameter: 2 µm), which is an alloy urea powder composed of and tantalum powder (average particle diameter: 9 µm) and tungsten powder (average particle diameter: 3 µm), and particle urea powder, respectively. These raw powders are each blended in an arbitrary ratio and mixed well to obtain a mixed powder (mixing step). Such mixed powder is molded into a cylindrical shape (ø16 × 32) by mold molding (molding step). Here, the molding pressure is 6 t / cm 2.

Subsequently, the molded body is heated in a vacuum of 1 × 10 ⁻⁵ Torr to a sintering temperature of 1300 ° C. from room temperature at the above temperature increase rate of 12.5 ° C./min, and maintained at this sintering temperature for 4 hours for sintering (sintering fair). Next, it cools at the cooling rate of 1 degree-C / s mentioned above (cooling process). The measurement sample (sample 13) used in the following measurement is obtained from the sintered compact obtained in this way.

About the sample 13, it carried out similarly to Example 1, and measures the composition of a matrix and the occupancy amount of the titanium boride particle | grains. The measurement results thereof are shown in Table 1.

In addition, the relative density with respect to the true density of the sample 13 was measured like Example 1, and the relative density is 98.5%. From this point of view, it was found that Sample 13 was also excellent in compactness.

(2) The stem portion is molded by hot extrusion at 1150 占 폚 using the sintered body described above.

Example 9: Sample 14

(1) Alloy element powder (average particle diameter) consisting of a commercially available hydrogenated dehydrogenated titanium powder (# 100) and an alloy powder having a composition of 30.7 Al-24.9 Sn-24.4 Zr-6.2 Nb-6.2 Mo-6.2 Hf-1.4 Si : 9 µm), Y ₂ O ₃ powder (average particle diameter: 3 µm) and TiB ₂ powder (average particle diameter: 2 µm), which are particle urea powders, were prepared, respectively. These raw powders are each blended in an arbitrary ratio and mixed well to obtain a mixed powder (mixing step). Such mixed powder is molded into a cylindrical shape (ø16 × 32) by mold molding (molding step). Here, the molding pressure is 6 t / cm 2.

Subsequently, the molded body is heated in a vacuum of 1 × 10 ⁻⁵ Torr to a sintering temperature of 1300 ° C. from room temperature at the above temperature increase rate of 12.5 ° C./min, and maintained at this sintering temperature for 4 hours for sintering (sintering fair). Next, it cools at the cooling rate of 1 degree-C / s mentioned above (cooling process). The measurement sample (sample 14) used in the following measurement is obtained from the sintered compact obtained in this way.

About the sample 14, it carried out similarly to Example 1, and measures the composition of a matrix and the occupancy amount of the titanium boride particle | grains. The measurement results thereof are shown in Table 1. In addition, the occupancy amount of the Y ₂ O ₃ particles is about 0.8% by volume.

In addition, the relative density with respect to the true density of the sample 14 was measured like Example 1, and the relative density is 98.5%. From this point of view, it was found that Sample 14 was also excellent in compactness.

(2) The stem portion is molded by hot extrusion at 1150 占 폚 using the sintered body described above.

[Comparative Example]

Comparative Example 1: Sample C1

① As raw material powders, the titanium powder to a commercially available hydrogenated dehydrogenation (# 100), Al-40V powder are prepared:: (mean particle size 2μm), respectively (mean particle size 3μm) and TiB ₂ powders. These raw material powders are blended in any ratio and mixed well with an Atolighter. Using the mixed powder thus obtained, a cylindrical (? 16 × 32) molded body is molded by mold molding. Here, the molding pressure is 6 t / cm 2.

Subsequently, the molded body is heated in a vacuum of 1 × 10 ⁻⁵ Torr to raise the temperature from room temperature to a sintering temperature of 1300 ° C. at the above-mentioned temperature rising rate of 12.5 ° C./min, and the sintering temperature is maintained for 4 hours to sinter. Next, it cools at the cooling rate of 1 degree-C / s mentioned above. The sample for measurement (sample C1) used in the following measurement is obtained from the sintered billet thus obtained.

The sample C1 was measured in the same manner as in Example 1, and the composition of the matrix and the occupancy of the titanium boride particles were measured. Table 2 shows the results of these measurements.

In addition, the relative density with respect to the true density of the sample C1 was measured like Example 1, and the relative density is 96.5%.

② The stem is formed by hot extrusion at 1150 ° C. in the same manner as in Example 5, using the sintered body described above. Next, the remaining portion is heated to 1150 ° C to form the head portion by forging. This is processed to produce an engine valve shown in FIG. 5B similarly to Example 1. FIG. In addition, in this comparative example, a crack occurs after extrusion.

Comparative Example 2: Sample C2

(1) Commercially available hydrogenated dehydrogenated titanium powder (# 100), alloy powder having a composition of 36.9 Al-24.9 Sn-24.4 Zr-6.2 Nb-6.2 Mo-1.4 Si (average particle diameter: 3 μm) and TiB ₂ powder ( Average particle diameter: 2 μm) are prepared respectively. These raw material powders are blended in any ratio and mixed well with an Atolighter. Using the mixed powder thus obtained, a cylindrical (? 16 × 32) molded body is molded by mold molding. Here, the molding pressure is 6 t / cm 2.

Subsequently, the molded body is heated in a vacuum of 1 × 10 ⁻⁵ Torr to raise the temperature from room temperature to a sintering temperature of 1300 ° C. at a temperature rising rate of 12.5 ° C./min as described above, and is maintained at this sintering temperature for 4 hours to sinter. It cools and sinters at the cooling rate of said 1 degree-C / s. The sample for measurement (sample C2) used in the following measurement is obtained from the sintered billet thus obtained.

About sample C2, it carried out similarly to Example 1, and measures the composition of a matrix and the occupancy amount of the titanium boride particle | grains. Table 2 shows the results of these measurements. In Sample C2, the average aspect ratio of the titanium boride particles was found to be 52, and the average particle diameter was 55 µm.

② The engine valve similar to the comparative example 1 is produced using said sintered compact.

Comparative Example 3: Sample C3

① As raw material powders, commercially available hydrogenated dehydrogenated titanium powder (# 100) and alloy powders (average particle diameter: 3 µm) each having a composition of 36.9 Al-24.9 Sn-24.4 Zr-6.2 Nb-6.2 Mo-1.4 Si were prepared. These raw material powders are blended in any ratio and mixed well with an Atolighter. Using the mixed powder thus obtained, a cylindrical (? 16 × 32) molded body is molded by mold molding. Here, the molding pressure is 6 t / cm 2.

Subsequently, these molded bodies are heated in a vacuum of 1 × 10 ⁻⁵ Torr to raise the temperature from room temperature to a sintering temperature of 1300 ° C. at a heating rate of 12.5 ° C./min as described above, and are maintained at this sintering temperature for 4 hours to sinter. Next, it cools at the cooling rate of 1 degree-C / s mentioned above. The sample for measurement (sample C3) used in the following measurement is obtained from the sintered billet thus obtained.

About sample C3, it carried out similarly to Example 1, and measures the composition of a matrix and the occupancy amount of the titanium boride particle | grains. Table 2 shows the results of these measurements.

In addition, the relative density with respect to the true density of sample C3 was measured like Example 1, and the relative density is 99%.

② The engine valve similar to the comparative example 1 is produced using said sintered compact.

Comparative Example 4: Sample C4

(1) Commercially available hydrogenated dehydrogenated titanium powder (# 100), alloy powder having a composition of 36.9 Al-24.9 Sn-24.4 Zr-6.2 Nb-6.2 Mo-1.4 Si (average particle diameter: 3 μm) and TiB ₂ powder ( Average particle diameter: 2 μm) are prepared respectively. These raw material powders are blended in any ratio and mixed well with an Atolighter. Using the mixed powder thus obtained, a cylindrical (? 16 × 32) molded body is molded by mold molding. Here, the molding pressure is 6 t / cm 2.

Subsequently, these molded bodies are heated in a vacuum of 1 × 10 ⁻⁵ Torr to raise the temperature from room temperature to a sintering temperature of 1300 ° C. at a heating rate of 12.5 ° C./min as described above, and are maintained at this sintering temperature for 4 hours to sinter. Next, it cools at the cooling rate of 1 degree-C / s mentioned above. The sample for measurement (sample C4) used in the following measurement is obtained from the sintered billet thus obtained.

About sample C4, it carried out similarly to Example 1, and measures the composition of a matrix and the occupancy amount of the titanium boride particle | grains. Table 2 shows the results of these measurements.

In addition, the relative density with respect to the true density of sample C4 was measured like Example 1, and the relative density is 96.5%. After extruding similarly to the sample C1 in the comparative example 1, a crack has arisen. From this, it was found that when the occupancy of the titanium boride particles exceeds 10% by volume, cracks are promoted and ductility decreases during extrusion.

② The engine valve similar to the comparative example 1 is produced using said sintered compact.

Comparative Example 5: Samples C5 and C6

① Prepare solvent forged heat-resistant titanium alloy (TIMETAL-1100) and use sample C5. Table 2 describes the composition of the alloy of Sample 5.

About sample C5, it melts by heating at 1050 degreeC, and performs annealing treatment at 950 degreeC.

(2) Using this titanium material, an engine valve having the same shape as in Example 1 was produced.

③ Prepare solvent forged heat-resistant titanium alloy (TIMETAL-834) and use it as sample C6.

Sample C6 was heated to 1027 ° C for solution, and then aged at 700 ° C.

Comparative Example 6: Sample C7

① Prepare heat resistant steel (SUH 35) and make it sample C7. Table 2 describes its alloy composition.

(2) An engine valve having the same shape as that of Example 1 was produced using this heat resistant steel.

[Evaluation of Strength, Creep, Fatigue and Wear Resistance]

Each sample or engine valve obtained in the above-described examples and comparative examples was subjected to the following tests, respectively, to evaluate the room temperature strength and the high temperature strength exceeding 610 ° C., creep property, fatigue property and wear resistance, respectively.

As for the strength, a tensile test is first performed with the sample at room temperature, and the values of tensile strength, 0.2% yield strength and elongation are respectively measured. Next, a tensile test is performed while the sample is heated to 800 ° C. and the value of 0.2% yield strength is measured. These results are shown in Table 3 and Table 4. In addition, the tensile test at room temperature is carried out at a strain rate of 4.55 x 10 ^-4 / s using an Instron tensile tester RT. In addition, the tensile test at high temperature is carried out at a strain rate of 0.1 / s at 800 ℃.

From Table 3 and Table 4, it is interpreted as follows.

① tensile strength

The 0.2% yield strength at room temperature is not significantly different between Samples 1 to 10 of Examples and Samples C1 to C6 of Comparative Examples.

However, the 0.2% yield strength at 800 ° C. shows that Samples 1 to 9 are higher than Samples C1, C3, C5 and C6.

In particular, Samples 2 to 9 often exhibit higher values of 0.2% yield strength at 800 ° C than Sample 1. This is considered to be because the matrix of each sample of Samples 2 to 9 contains 0.5 to 4.0% by weight of molybdenum and 0.5 to 4.0% by weight of niobium.

Samples 11 to 14 also have a high temperature strength of 400 MPa or more, and secure sufficient strength characteristics as the valve material.

② creep characteristics

In dry air, a creep test is performed in which a 50 MPa bending stress is applied to a sample heated to a temperature of 800 ° C., and creep characteristics are evaluated by measuring creep flexibility with respect to elapsed time. The measurement result about Example 3 (sample 3) and the comparative example 5 (sample C6) is shown in FIG. In FIG. 4, it turned out that the sample 3 has the creep characteristic in 800 degreeC exceeding sample C6.

In addition, although not shown here, it was found that all of the other samples 1 to 9 were excellent in creep characteristics.

③ fatigue characteristics

In the air, at room temperature, a rotational bending fatigue test is carried out to evaluate the fatigue properties at room temperature. As a result, 10 ⁷ times fatigue strength of about 750 MPa is obtained from the sample (Sample 5) of Example 4. On the other hand, in the sample (sample C2) of the comparative example 2, 10 ⁷ times the fatigue strength of 480 Mpa is obtained. From these, it turned out that Example 4 of this invention is excellent in fatigue strength at room temperature.

Moreover, high temperature fatigue characteristics are evaluated by heating to the temperature of 850 degreeC, and performing a rotational bending fatigue test. As a result, the Example 4 sample about the (Sample 5) In 10, the ^seven-fold, compared to Example 2 of the sample (sample C2) 10 ⁷ times, the sample (sample C5) of Comparative Example 5 of about 120MPa for about 175MPa 100MPa of 10 ⁷ times and 10 ⁷ times fatigue strength of about 150 MPa are obtained from the sample (Sample C7) of the comparative example 6. From these, it turned out that Example 4 of this invention is excellent also in the fatigue strength in high temperature.

④ Wear resistance

Wear resistance is assessed by the pin on disk test. In this test, when the pin wear amount is a result of ³ mg / 2 x 10 ³ m or less, excellent wear resistance is described in Tables 3 and 4 as ○. In addition, when a pin wear amount is a result of 10 mg / 2x10 <^3> m or more, it is described in Table 3 and Table 4 as x that abrasion resistance is inferior. As shown in Table 3 and Table 4, it turned out that all the samples of the Example were excellent in abrasion resistance.

⑤ durability

The full load high speed endurance test [practical endurance test] on the engine stand was performed on the engine valve shape | molded from the sintered compact obtained by Example 4 (sample 5) and the comparative example 3 (sample C3). do. And the wear amount in each site | part of a valve after a test is measured, and durability of abrasion resistance is evaluated. In addition, this practical skill endurance test is implemented on the test conditions of an average of 7000 rpm x 200 hr.

In this practical machine durability test, when it is below a predetermined reference wear amount, it is excellent in durability, and it describes in Table 3 and Table 4 as (circle). On the other hand, when the standard wear amount is exceeded or when the result of axial elongation or breakage is obtained, wear resistance is inferior, and it describes in Table 3 and Table 4 by x.

As shown in Table 3, it turned out that all the samples of this Example are excellent in wear resistance durability. This is considered to be because the titanium boride particles are finely and uniformly dispersed in the sample of this embodiment, so that cohesive wear hardly occurs.

[Dispersion Particles in Matrix]

As described above, as a result of examining the titanium-based composite material of the present invention in a multi-faced manner, the following points became clear again regarding the particles dispersed in the matrix. That is, although both the titanium compound particles and the rare earth compound particles dispersed in the titanium composite material of the present invention are effective in improving the heat resistance and the like of the titanium material, it has been found that the TiB particles are particularly effective in improving the heat resistance of the titanium composite material.

(1) For example, when comparing the sample (sample 5) of Example 4 with the sample (sample 11) of Example 6, sample 11 contains more aluminum than the sample 5 which is an alpha stabilizing element of a titanium alloy. Therefore, it is normally considered that the high temperature strength of the titanium-based composite material is larger in Sample 11 than in Sample 5. However, as can be seen from Table 3, sample 5 has a large high temperature strength in practice. In addition, Sample 5 is excellent in room temperature proof strength.

Comparing the two samples here, there is no significant difference in both compositions except for aluminum. Therefore, it is considered that the sample 5 has superior characteristics to the sample 11 due to the difference between the particles dispersed in the matrix, that is, the difference between the TiB particles dispersed in the sample 5 and the TiC particles dispersed in the sample 11. In other words, it is considered that TiB particles are superior to TiC particles as particles dispersed in a matrix in view of the strength-ductility balance of the titanium-based composite material.

Then, about the reason, three types of titanium compound particle | grains, TiB particle | grains, TiC particle | grains, and TiN particle | grains are taken and examined. The properties of each of these particles are shown in Table 5. For example, the following was found from Table 5 below.

Observing the mutual solid solubility of the matrix and these reinforcing particles, which greatly influences the strength-ductility balance of the titanium-based composite material, the mutual solid solubility between TiB particles and titanium, the matrix, is significantly higher than that of TiC particles and TiN particles. small. From this point of view, the TiB particles were found to be very stable particles in the titanium alloy. Accordingly, it is thought that the TiB particles sufficiently exhibit their own characteristics without weakening the matrix and are strengthening the titanium-based composite material along the composite side. On the other hand, since the TiC particles are somewhat dissolved in the matrix, the room temperature ductility of the titanium-based composite material is slightly lower than that of the TiB particles.

(2) The rare earth compound particles are also stable in the titanium alloy in the same manner as the TiB particles, but when more than 3% by volume is added, the sintered compact density decreases. Therefore, in the titanium-based composite material of the present invention as described above, it is effective to make the dispersion amount of the rare earth compound particles 3 vol% or less.

However, from the viewpoint of such sinterability, titanium compound particles, particularly TiB particles, are more effective than the rare earth compound particles because they can be dispersed in a large amount in the matrix.

(3) However, titanium compound particles such as rare earth compound particles and TiB particles have different chemical properties, but all of them have excellent stability and the like in titanium alloys, and they change to those particles which can improve the heat resistance of the titanium alloy. There is no Therefore, if a titanium-based composite material in which not only TiB particles but also titanium compound particles such as TiC particles or rare earth compound particles are dispersed in a matrix is used, for example, in an engine valve or the like, a lightweight engine valve having excellent heat resistance and durability can be obtained. Can be.

particle Longitude (GPa) Young's modulus (GPa) Coefficient of linear expansion (x10 ^-6 / K) Maximum high capacity (%) High doses of boron, carbon and nitrogen in the matrix High Capacity of Titanium in Particles TiB 28.0 550 8.6 <0.001 1.0 TiC 24.7 460 7.4 1.2 15.0 TiN 24.0 250 9.3 22.0 26.0 (Reference) The linear expansion coefficient of titanium alloy is about 9 × 10 ^-6 / K.

Since the titanium-based composite material of the present invention has excellent characteristics as described above, it can be used for automobile engine parts, various leisure and sporting goods and tools. In particular, according to the titanium-based composite material of the present invention, excellent strength, creep properties, fatigue properties and wear resistance can be obtained even at a very high temperature of 800 ° C. Thus, for example, it is a material suitable for automobile engine valves and the like. In particular, the titanium-based composite material of the present invention is used at high temperatures (e.g., near 800 ° C) such as exhaust valves, and is more suitable for use in parts requiring specific strength, fatigue resistance, and the like.

Claims (23)

3.0 to 7.0 weight percent aluminum (A1), 2.0 to 6.0 weight percent tin (Sn), 2.0 to 6.0 weight percent zirconium (Zr), 0.1 to 0.4 weight percent silicon (Si) and 0.1 to 0.5 weight percent A titanium-based composite material comprising a matrix composed mainly of a titanium alloy containing oxygen (O) and titanium compound particles dispersed in the matrix and occupying 1 to 10% by volume. 3.0 to 7.0 weight percent aluminum (Al), 2.0 to 6.0 weight percent tin (Sn), 2.0 to 6.0 weight percent zirconium (Zr), 0.1 to 0.4 weight percent silicon (Si) and 0.1 to 0.5 weight percent A titanium-based composite material comprising a matrix composed mainly of a titanium alloy containing oxygen (0) and rare earth compound particles dispersed in the matrix and occupying 3% by volume or less. 3.0 to 7.0 weight percent aluminum (A1), 2.0 to 6.0 weight percent tin (Sn), 2.0 to 6.0 weight percent zirconium (Zr), 0.1 to 0.4 weight percent silicon (Si) and 0.1 to 0.5 weight percent Titanium comprising a matrix composed mainly of a titanium alloy containing oxygen (0), titanium compound particles dispersed in the matrix and occupying 1 to 10% by volume and rare earth compound particles occupying 3% by volume or less System composite materials. The titanium-based composite material according to any one of claims 1 to 3, wherein the matrix contains 4.0 to 6.5% by weight of aluminum. The titanium-based composite material according to any one of claims 1 to 3, wherein the matrix contains 2.5 to 4.5 wt% tin. The titanium-based composite material according to any one of claims 1 to 3, wherein the matrix contains 2.5 to 4.5 wt% zirconium. The titanium-based composite material according to any one of claims 1 to 3, wherein the matrix contains 0.15 to 0.4 wt% silicon. The titanium-based composite material according to any one of claims 1 to 3, wherein the matrix contains 0.15 to 0.4% by weight of oxygen. The titanium-based composite material according to any one of claims 1 to 3, wherein the matrix further contains 0.5 to 4.0 wt% molybdenum (Mo) and 0.5 to 4.0 wt% niobium (Nb). The titanium-based composite material according to claim 9, wherein the matrix contains 0.5 to 2.5 wt% molybdenum. The titanium-based composite material according to claim 9, wherein the matrix contains 0.5 to 1.5 wt% niobium. The titanium-based composite material according to claim 9, wherein the matrix further contains at least one metal element of tantalum (Ta), tungsten (W), and hafnium (Hf) of 5 wt% or less in total. The titanium compound particles according to any one of claims 1 to 3, wherein the titanium compound particles are at least one particle of titanium boride, titanium carbide, titanium nitride and titanium silicide, and the rare earth compound particles are yttrium (Y) and cerium (Ce). And titanium-based composite material which is at least one particle of an oxide and a sulfide of lanthanum (La), erbium (Er), and neodymium (Nd). The titanium-based composite material according to claim 13, wherein the titanium compound particles are particles consisting of TiB and / or TiC, and the rare earth compound particles are particles constituting Y ₂ O ₃ . The titanium-based composite material according to any one of claims 1 to 3, wherein the titanium compound particles and / or the rare earth compound particles have an average aspect ratio of 1 to 40 and an average particle diameter of 0.5 to 50 µm. The titanium-based composite material according to any one of claims 1 to 3, which exhibits a 0.2% yield strength of 400 MPa or more at 800 ° C or more. A matrix composed mainly of a titanium alloy containing 3.0 to 7.0 wt% aluminum, 2.0 to 6.0 wt% tin, 2.0 to 6.0 wt% zirconium, 0.1 to 0.4 wt% silicon and 0.1 to 0.5 wt% oxygen; A method for producing a titanium-based composite material having titanium compound particles dispersed in the matrix and occupying 1 to 10 vol% and / or rare earth compound particles occupying 3 vol% or less, A mixing process of mixing titanium powder, alloy urea powder containing aluminum, tin, zirconium, silicon and oxygen with particle urea powder forming titanium compound particles and / or rare earth compound particles, A molding step of molding a green compact having a predetermined shape using the mixed powder obtained in the mixing step, A sintering step of sintering the molded product obtained in the molding step at a temperature above the β transformation point to generate a β phase A method for producing a titanium-based composite material, comprising a cooling step of depositing an α phase from a β phase. The method for producing a titanium-based composite material according to claim 17, wherein the sintering step sets the sintering temperature to 1200 to 1400 ° C and the sintering time to 2 to 16 hours. The method for producing a titanium-based composite material according to claim 17, wherein the cooling step includes a cooling step with a cooling rate of 0.1 to 10 (占 폚 / s). The process of claim 17, wherein the mixing step is a process of mixing titanium powder having an average particle diameter of 10 to 200 μm, alloy urea powder having an average particle diameter of 5 to 200 μm, and particle urea powder having an average particle diameter of 1 to 30 μm. Method for producing titanium based composite material. 3.0 to 7.0 weight percent aluminum (Al), 2.0 to 6.0 weight percent tin (Sn), 2.0 to 6.0 weight percent zirconium (Zr), 0.1 to 0.4 weight percent silicon (Si) and 0.1 to 0.5 weight percent An engine valve using a titanium-based composite material comprising a matrix composed mainly of a titanium alloy containing oxygen (0) and titanium compound particles dispersed in the matrix and occupying 1 to 10% by volume or less. 3.0 to 7.0 weight percent aluminum (A1), 2.0 to 6.0 weight percent tin (Sn), 2.0 to 6.0 weight percent zirconium (Zr), 0.1 to 0.4 weight percent silicon (Si) and 0.1 to 0.5 weight percent An engine valve using a titanium-based composite material comprising a matrix composed mainly of a titanium alloy containing oxygen (O) and rare earth compound particles dispersed in the matrix and occupying 3% by volume or less. 3.0 to 7.0 weight percent aluminum (Al), 2.0 to 6.0 weight percent tin (Sn), 2.0 to 6.0 weight percent zirconium (Zr), 0.1 to 0.4 weight percent silicon (Si) and 0.1 to 0.5 weight percent A titanium-based composite material comprising a matrix composed mainly of a titanium alloy containing oxygen (O), titanium compound particles dispersed in the matrix and occupying 1 to 10% by volume and rare earth compound particles occupying 3% by volume or less. Used engine valve.